Phytochemicals are substances that plants naturally produce to protect themselves against bacteria, viruses, and fungi. There has been a lot of interest in phytochemicals recently because many of them have demonstrated effects on slowing the aging process and reduce the risk for cancer, heart disease, and other chronic health conditions.
More than 900 different phytochemicals have been found in plant foods, with others still to be discovered. Fruits, vegetables, whole grains, soy and nuts are all sources of these disease-fighting substances. Phytochemicals are usually related to plant pigments, so fruits and vegetables with bright colors (yellow, orange, red, blue, purple, green) contain the most.
Flavonoids are a group of phytochemicals that have long been recognized to possess anti-inflammatory, antioxidant, antiallergic, hepatoprotective, antithrombotic, antiviral, and anticarcinogenic activities. The flavonoids are typically phenolic compounds and, therefore, act as potent metal chelators and free radical scavengers. They are powerful chain-breaking antioxidants. The flavonoids display a remarkable array of biochemical and pharmacological actions, some of which suggest that certain members of this group of compounds may significantly affect the function of various mammalian cellular systems. Recent reports indicate that plant flavonoids cause the activation of bacterial (Rhizobium) modulation genes involved in control of nitrogen fixation, which suggests important relationships between particular flavonoids and the activation and expression of mammalian genes (See e.g., Midddledton et al., Pharmacological Reviews, 2000, 52:673-751).
Tectorigenin is a flavonoid. In recently years, development has been made in exploring the potential utility of tectorigenin, which has demonstrated anti-bacterial, anti-inflammatory, and cancer-preventing activities. Moreover, it has been shown that tectorigenim stimulates the production of prostaglandin, induces proliferation of macrophages, selectively modulates the activity of estrogen receptors, and controls smooth muscle contraction.
Tectorigenin is typically extracted from rhizomes of Iridaceae plants, such as Iris germanica L., Iris pallida Lam, Iris nigricans, Iris ensata, Iris sanguinea, Iris setosa, and Belamacanda chinensis (B. chinensis). The tectorigenin content in the rhizomes are affected by the growth conditions, such as temperature and humidity. In the case of B. chinensis, it usually takes 2-3 years of growth before the rhizomes can be harvested for tectorigenin extraction. Therefore, there still exists a need for methods that can effectively grow plants with a high tectorigenin content.
Neomarica gracilis (N. gracilis) is a very common horticulture plant that belongs to the Iridaceae family. It can be cultured in large scale at low cost. However, the rhizomes of naturally grown N. gracilis does not contain tectorigenin.
In the invention to be presented in the later sections, an in vitro rhizome of N. gracilis is obtained from a tissue culture preparation, which can be harvested in about 1 or 2 months. The in vitro rhizome of N. gracilis is rich in flavonoids and contains high content of tectorigenin, which can be used as a source for tectorigenin.